This is how I mount the removable hatch on my Viking.
Two screws hold it down - one just behind the engine and one at the rear.
It has worked perfectly for twenty eight years.
Since it needed almost an ounce of tailweight, I moved the engine (OK Super 60) back 7/8 inch.
As seen, there is still plenty of room for the tank (2 ounces), coil, batteries switch and condenser.
Bob Z.